electroweak interactions topical group

Electroweak Interactions Topical Group

Conveners

Wolfgang Kilian, University of SiegenTheory

Taikan Suehara, Kyushu UniversityExperiment

Graham Wilson, University of KansasExperiment

Graham W. Wilson ILC Physics Potential WG Kickoff May 27, 2021 1 / 7

The e+e− LandscapeILC: polarized e− (80%) and e+ (30%). No trigger needed. Use all decay modes.

Unpolarized cross-sections

Study electroweak physics with 2f, 4f, 6f, 8f. Ranging from the Z-pole to√s

conceivably around 1 TeV. Expect ZH, WWZ, WWH, ZZZ, ZZH, ZHH, tt,WWWW, WWZZ, ttH within reach of 500 GeV collider.


Electroweak Physics Channels

Di-fermion production, e+e− → ff with f = e, µ, τ, q (q=u,d,s,c,b,t)

Radiative di-fermion production, e+e− → ffγ.Especially µ+µ−γ, ννγ and qqγ.

Di-boson production. Mainly 4-fermion final states resulting from WW, ZZ,ZH, but also Zγ, γγ.

Multiple-boson production. Mainly 6-fermion final states (from WWZ,WWH, ZZZ, ZZH, ZHH), but also WWγ, ZHγ, Zγγ.

Other processes. 4f: single Z, (eeZ and ννZ), single W (Weνe). ννγγ etc.

Quartic boson production

Alternative collider modes (e−e−, e−γ and γγ)

1 Zf f couplings

2 WWγ and WWZ trilinear couplings

3 quartic couplings (WWWW, WWZZ, WWZγ and WWγγ)


Some Physics Goals and Questions I

Z couplings to fermions

Study the potential improvements in Z observables from a dedicated Z polerun with polarized beams and line-shape scan. Evaluate detector andaccelerator requirements. Key issue: excellent understanding of

√s scale.

Utility of radiative return events for Z physics?

How can precision Z couplings test BSM models?

Importance of polarized observables (key asset of ILC)

How can 2-fermion measurements at the highest energies constrain newphysics?

Are final-state polarization measurements with tau leptons important at thehighest energies? Quantify related detector requirements.

· · ·


Some Physics Goals and Questions II

WW program

Define the ILC experimental program on W boson pair production. What arethe key observables and detector requirements?

What are the various ways to measure the W boson mass at the ILC andultimate precision? Is a run at threshold well motivated?

How can one best achieve a precision measurement of the W width?

Can ILC measure the polarized production amplitudes in a modelindependent way?

What BSM models are tested by this program?

What advances in theory are needed to fully exploit 108 WW events?

Can one fully utilize massive gauge boson reconstruction in hadronic decays?

· · ·Graham W. Wilson ILC Physics Potential WG Kickoff May 27, 2021 5 / 7

Some Physics Goals and Questions III

Other weak boson processes and generic questions

What are the ILC capabilities to study the other weak boson reactionsincluding triple-boson, four-boson production and vector-boson scattering?

Can all the various processes be analyzed coherently with the other EWmeasurements including in global fits.

How well can the quartic couplings be isolated and measured?

Explore the complementarity of the direct multi-boson production with VBS

Direct CKM matrix element measurements from W decays

Rare decays of the W

Lepton universality tests in W decays, Z decays, and tau decays

Does the Z couple to uu/dd/ss/cc/bb as described in SM?

Can WW and ZZ be used to learn about color reconnection?

· · ·Graham W. Wilson ILC Physics Potential WG Kickoff May 27, 2021 6 / 7

Concluding Remarks

Relations to other topical groups and task forces

Almost all of the task forces will be very pertinent to EW physics

Some overlap/cross-talk of course with other groups

Questions

Many interesting questions to explore

What interests you? Do you have ideas on complementary topics?

Invitation

We welcome experimentalists and theorists to join:

share your perspective

better understand the capabilities of the ILC for electroweak physics

inform the detector and accelerator design

Recent documentation on physics ideas, SM tests, and the ILC project in Refs. [1, 2, 3]


References I

[1] K. Fujii et al., [LCC Physics Working Group],ILC Study Questions for Snowmass 2021, arXiv:2007.03650

[2] K. Fujii et al. [LCC Physics Working Group],Tests of the Standard Model at the International Linear ColliderarXiv:1908.11299

[3] P. Bambade et al.The International Linear Collider: A Global Project, arXiv:1903.01629


https://arxiv.org/abs/2007.03650



electroweak interactions topical group

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